Field of the Invention
The invention generally relates to coexistence of two or more signals in a wireless environment, and more specifically to achieving coexistence using a collision avoidance approach.
Related Art
Wireless devices, such as smart phones, for example, today integrate multiple radio access technologies (RATs) on a single device, including 4G (e.g., Long Term Evolution (LTE)), 3G, 2G, Wireless Local Area Network (WLAN), WiFi, Bluetooth (BT), Global Position System (GPS), among others. Due to the close proximity of the radio devices of the multiple RATs, the transmission of a first RAT can potentially interfere with the reception of a second RAT, despite the fact that the two RATs operate on separate frequency bands. For instance, BT/WiFi operating in the ISM (Industrial, Scientific, and Medical) band, for example, can impact LTE operating in bands 7, 38, 40 and 41.
Existing solutions for mitigating interference between co-located RATs may be classified into two main categories. A first category includes adding sharp transmit and receive filters in the transceivers of the co-located RATs. A significant disadvantage of the first category of solutions is the increase in the bill of material (BOM) and the overall area/size of the platform due to the bulky acoustic type filters that must be added. Other disadvantages of this approach include increased noise figure at the receiver and increased insertion loss at the transmitter, both of which compromise the link performance and system throughput.
A second category of existing solutions includes scheduling and coordination between the RATs to insure that the RATs are never transmitting and/or receiving a signal at the same time. This approach includes preventing all concurrent transmissions and receptions, and all situations where one RAT is transmitting and another RAT is concurrently receiving. A main problem with the second category is that it sacrifices system throughput in order to reduce interference. This scheduling approach may also require changes to the air interface standards due to necessary signaling between the user equipment and the base station, for example.
Thus, neither of the existing solutions effectively mitigates intermodulation between co-located RATs.
Embodiments of the disclosure will now be described with reference to the accompanying drawings. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the reference number